As far as Wayland goes, that is up to the developers and users of those compositors. The protocol itself supports the concept of multiple seats.

I can't speak for all the original X developers but TFA seems to suggest that they didn't think it all through.

When X is matched, then we can discuss whether that is true.

Currently, it's not. That does not make current efforts bad. I think they are quite nice.

They just do not yet actualize the vision X did and does today.

Whether that is wanted / needed is also an open discussion at this time.

It won't be matched unless someone sees enough of a need to make it happen. Wayland the protocol doesn't have an explicit goal of doing everything that X did. The design is different.

As far as I can tell, the original vision of X was to unify all the proprietary Unix vendors with a standard windowing protocol. The network capabilities happened because they wanted to support dumb terminals connected to mainframes. Most of those proprietary Unix vendors are now gone. Currently it's not clear to me what role X is supposed to have, if any.

The role is multi user graphical computing. I made comments elsewhere in thread about that.

We may find or choose for that to not be a thing.

Ok, fine.

The X window people did make that a thing and the end result is powerful and flexible.

None of that makes efforts like Wayland bad. They aren't.

But they, by your own definition, are a subset of what X is too. They aren't thinking it through, by design. That is OK.

Wayland (the protocol) supports the necessary bits and it's up to the compositors if they want to go the extra mile to support everything.

My own personal take is that most compositors won't because X does not represent multi user graphical computing in the way that most people use it today. That role is fulfilled by web applications.

Commercial UNIX vendors, Xerox, TI, Genera, were already doing that before X was created.